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<title>sum - Cyclic Redundancy Checks</title>
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<div class="doctools">
<h1 class="doctools_title">sum(n) 1.1.2 tcllib &quot;Cyclic Redundancy Checks&quot;</h1>
<div id="name" class="doctools_section"><h2><a name="name">Name</a></h2>
<p>sum - Calculate a sum(1) compatible checksum</p>
</div>
<div id="toc" class="doctools_section"><h2><a name="toc">Table Of Contents</a></h2>
<ul class="doctools_toc">
<li class="doctools_section"><a href="#toc">Table Of Contents</a></li>
<li class="doctools_section"><a href="#synopsis">Synopsis</a></li>
<li class="doctools_section"><a href="#section1">Description</a></li>
<li class="doctools_section"><a href="#section2">COMMANDS</a></li>
<li class="doctools_section"><a href="#section3">OPTIONS</a></li>
<li class="doctools_section"><a href="#section4">EXAMPLES</a></li>
<li class="doctools_section"><a href="#section5">AUTHORS</a></li>
<li class="doctools_section"><a href="#section6">Bugs, Ideas, Feedback</a></li>
<li class="doctools_section"><a href="#see-also">See Also</a></li>
<li class="doctools_section"><a href="#keywords">Keywords</a></li>
<li class="doctools_section"><a href="#category">Category</a></li>
<li class="doctools_section"><a href="#copyright">Copyright</a></li>
</ul>
</div>
<div id="synopsis" class="doctools_section"><h2><a name="synopsis">Synopsis</a></h2>
<div class="doctools_synopsis">
<ul class="doctools_requirements">
<li>package require <b class="pkgname">Tcl 8.2</b></li>
<li>package require <b class="pkgname">sum <span class="opt">?1.1.2?</span></b></li>
</ul>
<ul class="doctools_syntax">
<li><a href="#1"><b class="cmd">::crc::sum</b> <span class="opt">?<i class="arg">-bsd</i> | <i class="arg">-sysv</i>?</span> <span class="opt">?<i class="arg">-format fmt</i>?</span> <span class="opt">?<i class="arg">-chunksize size</i>?</span> [ <i class="arg">-filename file</i> | <i class="arg">-channel chan</i> | <i class="arg">string</i> ]</a></li>
</ul>
</div>
</div>
<div id="section1" class="doctools_section"><h2><a name="section1">Description</a></h2>
<p>This package provides a Tcl-only implementation of the sum(1) command
which calculates a 16 bit checksum value from the input data.  The BSD
sum algorithm is used by default but the SysV algorithm is also
available.</p>
</div>
<div id="section2" class="doctools_section"><h2><a name="section2">COMMANDS</a></h2>
<dl class="doctools_definitions">
<dt><a name="1"><b class="cmd">::crc::sum</b> <span class="opt">?<i class="arg">-bsd</i> | <i class="arg">-sysv</i>?</span> <span class="opt">?<i class="arg">-format fmt</i>?</span> <span class="opt">?<i class="arg">-chunksize size</i>?</span> [ <i class="arg">-filename file</i> | <i class="arg">-channel chan</i> | <i class="arg">string</i> ]</a></dt>
<dd><p>The command takes string data or a file name or a channel and returns
a checksum value calculated using the <b class="syscmd">sum(1)</b> algorithm. The
result is formatted using the <i class="arg">format</i>(n) specifier provided or as
an unsigned integer (%u) by default.</p></dd>
</dl>
</div>
<div id="section3" class="doctools_section"><h2><a name="section3">OPTIONS</a></h2>
<dl class="doctools_definitions">
<dt>-sysv</dt>
<dd><p>The SysV algorithm is fairly naive. The byte values are summed and any
overflow is discarded. The lowest 16 bits are returned as the
checksum.  Input with the same content but different ordering will
give the same result.</p></dd>
<dt>-bsd</dt>
<dd><p>This algorithm is similar to the SysV version but includes a bit rotation
step which provides a dependency on the order of the data values.</p></dd>
<dt>-filename <i class="arg">name</i></dt>
<dd><p>Return a checksum for the file contents instead of for parameter data.</p></dd>
<dt>-channel <i class="arg">chan</i></dt>
<dd><p>Return a checksum for the contents of the specified channel. The
channel must be open for reading and should be configured for binary
translation. The channel will no be closed on completion.</p></dd>
<dt>-chunksize <i class="arg">size</i></dt>
<dd><p>Set the block size used when reading data from either files or
channels. This value defaults to 4096.</p></dd>
<dt>-format <i class="arg">string</i></dt>
<dd><p>Return the checksum using an alternative format template.</p></dd>
</dl>
</div>
<div id="section4" class="doctools_section"><h2><a name="section4">EXAMPLES</a></h2>
<pre class="doctools_example">
% crc::sum &quot;Hello, World!&quot;
37287
</pre>
<pre class="doctools_example">
% crc::sum -format 0x%X &quot;Hello, World!&quot;
0x91A7
</pre>
<pre class="doctools_example">
% crc::sum -file sum.tcl
13392
</pre>
</div>
<div id="section5" class="doctools_section"><h2><a name="section5">AUTHORS</a></h2>
<p>Pat Thoyts</p>
</div>
<div id="section6" class="doctools_section"><h2><a name="section6">Bugs, Ideas, Feedback</a></h2>
<p>This document, and the package it describes, will undoubtedly contain
bugs and other problems.
Please report such in the category <em>crc</em> of the
<a href="http://core.tcl.tk/tcllib/reportlist">Tcllib Trackers</a>.
Please also report any ideas for enhancements you may have for either
package and/or documentation.</p>
<p>When proposing code changes, please provide <em>unified diffs</em>,
i.e the output of <b class="const">diff -u</b>.</p>
<p>Note further that <em>attachments</em> are strongly preferred over
inlined patches. Attachments can be made by going to the <b class="const">Edit</b>
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar.</p>
</div>
<div id="see-also" class="doctools_section"><h2><a name="see-also">See Also</a></h2>
<p><a href="cksum.html">cksum(n)</a>, <a href="crc32.html">crc32(n)</a>, sum(1)</p>
</div>
<div id="keywords" class="doctools_section"><h2><a name="keywords">Keywords</a></h2>
<p><a href="../../../../index.html#checksum">checksum</a>, <a href="../../../../index.html#cksum">cksum</a>, <a href="../../../../index.html#crc">crc</a>, <a href="../../../../index.html#crc32">crc32</a>, <a href="../../../../index.html#cyclic_redundancy_check">cyclic redundancy check</a>, <a href="../../../../index.html#data_integrity">data integrity</a>, <a href="../../../../index.html#security">security</a>, <a href="../../../../index.html#sum">sum</a></p>
</div>
<div id="category" class="doctools_section"><h2><a name="category">Category</a></h2>
<p>Hashes, checksums, and encryption</p>
</div>
<div id="copyright" class="doctools_section"><h2><a name="copyright">Copyright</a></h2>
<p>Copyright &copy; 2002, Pat Thoyts &lt;patthoyts@users.sourceforge.net&gt;</p>
</div>
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